In addition to these requirements, various others occasionally pop up, such as support for Mycenaean Greek, Linear A/B, various obscure manuscript ligatures, Tocharian (not yet encoded in Unicode), etc. However, these are so obscure that I would not expect a generally linguistics-oriented font to support them; there are specialist fonts for them.
Consider adding more scripts to Darwin after almost everything has been finished. Possible scripts:
With some mild amount of insanity:
With great insanity:
Historical scripts, as noted by Janus Bahs Jacquet:
Requested minority scripts: